The present invention is directed to an improved microwave lamp, and particularly to such a lamp which is compact and has improved reliability.
Microwave lamps are well known, and typically include a means for providing microwave power, such as a magnetron, a bulb containing a discharge forming fill, and a means for coupling the microwave power to the bulb. Additionally, in many microwave lamps, the bulb is rotated. This is because bulb rotation affords numerous advantages, including temperature equalization around the bulb surface, improved spatial emission properties, discharge stabilization, elimination of visual "wobble", increased efficiency, and better cooling in those lamps where forced air cooling is applied to the bulb. For example, see U.S. Pat. Nos. 4,485,332, 4,695,757, 4,954,756, and U.S. Pat. No. 5,493,184, and co-pending U.S. application Ser. Nos. 08/811,466 and 08/811,467.
It is also a requirement in microwave lamps to provide cooling of the magnetron, and this is usually done by using a blower to provide forced air cooling. In the microwave lamps of the prior art, separate motors are used to rotate the bulb and to operate the blower.
As mentioned above, in some microwave lamps, notably those which operate at high power density, the bulb is also cooled by forced air. In such lamps, a separate motor may also be used to operate a compressor which provides the forced air for bulb cooling.